Circuit breaker with circulating oil arc quenching means



Oct. 25, 1966 E. MARX ET AL 3,281,561

CIRCUIT BREAKER WITH CIRCULATING OIL ARC QUENCHING MEANS Filed July 12, 1963 5 Sheets-Sheet 1 K HOLGER ANN GHIM SCI/APER FRIED KRUGKEWITT RUDOLF 5$KOPF DIETER 1G OTTO APOSTEL By W 1% Oct. 25, I966 E. MARX ETAL 3,281,561

CIRCUIT BREAKER WITH CIRCULATING OIL ARC QUENCHING MEANS Filed July 12, 1963 5 Sheets-Sheet a Jnvenfars ERWIN MARX efa/ a, mt m imw A/fameys Oct. 25, 1966 E. MARX ETAL CIRCUIT BREAKER WITH CIRCULATING OIL ARC QUENCHING MEANS Filed July 12, 1963 5 Sheets-Sheet 5 '1!!! Ill/fill Jn venfars ERW/N MARX efa/ fly Affomavs Oct. 25, 1966 E. MARX ETAI.

CIRCUIT BREAKER WITH \OIRCULATING OIL ARC QUENCHING MEANS Filed July 12, 1963 5 Sheets-Sheet 5 J0 ven tors w a w H mm A/ M A N? R E Byj United States Patent 3,281,561 CIRCUIT BREAKER WITH CIRCULATING OIL ARC QUENCHING MEANS Erwin Marx, Am Hohen Felde 7, Braunschweig, Germany; Adil Erk, Liebermanustrasse 17, Braunschweig, Germany; Holger Ann, Erlenweg 6, Wolfenbuttel, Germany; Joachim Schaper, Seillwinderstrasse 3, Hannover, Germany; Wilfried Kruckewitt, Bultenweg 27a, Brannschweig, Germany; Rudolf Grosskopf, Sieberstrasse 44, Herzberg/Harz, Germany; Dieter Kiinig, Am Qualenberg 11, Klein Stockheim, near Braunschweig, Germany; and Otto Apostel, Zimmerstrasse 4, Braunschweig, Germany Filed July 12, 1963, Ser. No. 294,685 Claims priority, application Germany, May 4, 1963,

M 56,698; July 16, 1962, M 53,582

Claims. (Cl. 200-150) The present invention relates to circuit breakers. More particularly, the present invention relates to circuit breakers for high voltage direct current circuit networks with fluid type are extinguishing.

It is an object of the present invention to provide for a new circuit breaker in which a high are voltage drop is being produced with the utmost speed and being maintained until current cut off. Such object is important for high voltage D.C. networks but also for networks operating at low technical frequencies (16 /3, 20, 50 or 60 c.p.s.). The electric current has to be turned off at times independent from any natural oscillatory passage through zero.

In case, for example, a DC. circuit is to be interrupted, the magnetic energy stored therein will have to be dissipated at least partially in and by the arc, i.e. such energy must be converted into heat. Hence, a network normally operating at high voltages requires an arc voltage drop correspondingly high and to be maintained sufficiently long if the amount of stored magnetic energy to be dissipated is rather high.

According to one aspect of the present invention in a preferred embodiment thereof it is suggested to provide for the following elements and arrangements inside of a circuit breaker housing. There are first two lead-in conductor rods, each terminating in mutually engagea-ble and separable contact pieces. The contact pieces are enveloped by walls preferably pertaining to a tube or the like and defining an oil filled cavity. An insulating plate is movably disposed for moving into the interior of the cavity and in between the two contact pieces to carry away therefrom any are developed between them. The insulating plate has a leading edge to move the central portion of the are within the oil, thereby cooling this arc portion extensively, and the arc is extended simultaneously therewith.

The insulating plate will preferably be used also as primary contact piece separator for initiating the actual circuit breaking. The contact pieces have to be spread apart to such an extent only that the insulating plate can pass. This path of spreading is in effect a very small distance only. The insulating plate extends primarily in directions perpendicularly to the arc.

After initial contact separation, the plate moves rapidly to carry away with its leading edge the are as aforementioned. There will be formed immediately a vapor bubble around the are, but the leading edge of the insulating plate continuously moves the arc towards the boundary walls of this bubble so that fresh and cool oil is continuously brought into engagement with the arc. Measuring tests have shown that the arc voltage can be increased up to 800 volts per centimeter arc length as compared with the known l0 0-200 volts per centi meter attainable in conventional circuit breakers.

After the arc has extinguished, the circuit breaker offers its insulating wall as stationary insulation between the separated contact pieces. This insulation effect is en- .hanced by the fact that the cavity will still be filled with oil submerging contact pieces as well as the now resting insulating plate.

As will be more-fully explained later in this specification, it is desirous to additionally and homogeneously place cooling oil into heat exchange relationship with the entire arc, even though the latter is being continuously extended so that the voltage drop per unit arc length remains fairly uniform along the arc; accordingly, it is desirous to have a large voltage drop per centimeter along the entire are for a production of a large overall arc voltage drop between the contact pieces,

As will also be more fully explained in detail with reference to the appended drawings, further features supplementing the basic inventive concept are the following: the cavity defining means are to be provided with charge and discharge channels to flush the are along its entire extension without causing the arc to deflect away from the flow of cooling oil. Such channels may be arranged in' a mesh like manner or as superimposed slots separated by straps.

The channels as well as other wall elements coming more or less in the vicinity of the arc will be provided with a gas producing and dispensing substance. Also, the leading wall edge carrying the arc may have gas dispensing substances. Detonator charges are being used to propel the insulating plate in between the contact pieces and/or to accelerate cooling liquid into the arc area.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects, and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawing in which:

FIGURE 1 illustrates a cross-sectional view into a circuit breaker constituting a first embodiment of the invention and being shown in contact making position;

FIGURE La illustrates a modified detail of the device shown in FIGURE 1, also in cross-sectional view;

FIGURE 2 illustrates the circuit breaker of FIGURE 1 during contact breaking;

FIGURE 3 illustrates the circuit breaker of FIGURE 1 after completion of circuit breaking;

FIGURES 4 and 5 illustrate cross-sectional views in planes 44 and 55 respectively shown in FIGURE 1;

FIGURE 6 illustrates a modification of the arc-receiving cavity of the circuit breaker shown in FIGURES 1 to 5;

FIGURE 7 illustrates a further modification of the said arc receiving cavity;

FIGURES 8, 9 and 10 illustrate in side elevation examples for the profile of the leading edge of the insulating plate shown as are and contact pieces control element in FIGURES 1 through 7.

FIGURE 11 illustrates in cross-sectional view a further modification of the said arc receiving cavity;

FIGURE 12 illustrates in cross-sectional view a circuit breaker according to another embodiment of the invention showing current responsive oil flow control means;

FIGURE 13 illustrates in cross-sectional View an electromag'netic agitator which can be employed in any of the aforedescribed embodiments;

FIGURE 14 illustrates a cross-sectional view through a circuit breaker according to another embodiment of the invention;

FIGURE 15 illustrates a cross-sectional view of plane AA of the circuit breaker illustrated in FIGURE 14; I FIGURES l6 and 17 show front and side elevation,

.respectively of a detailed channel section of the circuit breaker shown in FIGURES l4 and 15; and

FIGURES 18 and 19 illustrate in cross-sectional view two modifications of the circuit breaker as illustrated in FIGURE 15.

Proceeding now to the detailed description of the drawing, in FIG. 1 thereof there are shown electric current lead-in conductor rods 1 with wall tube insulators 2 for running the conductors into the usually metallic circuit breaker housing 9. The two conductor rods 1 terminate in contact pieces 3 and 4 which contact pieces are located in the lower portion of a space or cavity 7 defined by stationary and contiguous walls 5 and 6. Cavity 7 is filled with oil, so is the main part of housing 9.

Whenever the circuit breaker is closed (as shown in FIG. 1) the contact pieces 3 and 4 are urged towards each other by means of springs (not shown-conventional). Cavity 7 as defined by walls 5 and 6 communicates with the interior space of housing 9 by means of slanted apertures or gas discharge channels 8. The purpose of these apertures is to provide for pressure equalization between cavity 7 and interior space 10. In the area of the apertures cavity 7 may have a width of only a few millimeters.

The drawing shows two sets of apertures 8 at the left hand side and the right hand side of cavity 7, illustrating that these apertures or discharge channels do not have to be uniformly spaced from each other nor do they have to be of similar width.

A solid and sturdy wall or plate 11 is normally located below the contact pieces 3 and 4. Plate 11 consists of electrically insulating material, and it runs in guiding grooves 12 carved into the Walls 5. Grooves 12 extend downwardly into the stationary wall 13 enclosing a cylindrical cavity 14 communicating with cavity 7. Insulating plate 11 stays in cavity 14 as long as the contact pieces are in contact making position. Plate 11 is movable and rests with its lower edge 15 loosely upon a piston 16. The resting position is assumed by plate 11 whenever the circuit breaker is being closed. The lower part of cavity 14 has openings 14a for oil recirculation.

Piston 16 is connected securely to a lower piston 18 by means of a piston rod 17. Beneath piston 18 there is positioned a detonating charge 18 actually closing cavity 14 from below. When the charge 19 is fired, piston 18 is propelled upwardly, thereby carrying along rod 17 and piston 16 at a rapid motion. Since insulating plate 11 rests on piston 16, it is likewise pushed upwardly.

In the alternative, the insulating plate 11 may be propelled by means of an electromagnetic drive. For example, the piston 18 may be a magnetic core, and an energizable electric coil is embedded in the lower part of housing 9 or of walls 13 to rapidly move the assembly 1715-11 upward when required.

Insulating plate 11 has an upper operating area 20 at its leading edge urging contact pieces 3 and 4 apart. Thus, plate 11 serves as contact separator initiating and causing circuit breaking.

The primary function of insulator plate 11 is, however, a different one, and will be explained below. Thus, the contact pieces 3 and 4 may be urged apart for contact breaking in a difierent manner. For reasons of economy, however, it is quite appropriate to assign multiple function to individual elements and the device as illustrated of course, strong enough to propel piston 18 into its uppermost position.

The lower portion of tube 13 is provided with outlets 13a so as to avoid a cushioning of the air above piston 18.

At least during the initial portion of upward propelling, piston 18 should move freely.

FIGURE 2 now shows by the dotted line the configuration of the arc 21 developed between contact pieces 3 and 4 upon separation thereof. The configuration of the arc is not idealized but is, in fact, a more or less regular V.

The upward movement of insulating plate 11 extends the length of the arc. The bend of the V is seated on the leading or control edge 20 of insulating plate 11 and leads the movement of the are into the coil of space 7. Moreover, this central portion of are 21 contacts continuously fresh and still cool oil, so that this central arc portion is strongly being cooled indeed. Necessarily, a high are voltage will result from this cooling, and the arc will extinguish when the insulating wall 11 with front face 20 reaches the upper region of apertures 8.

Since the contact pieces 3 and 4 are to be of light weight, the insulating plate 11 can be also very light indeed. Thus, the power available sufiices to extend the arc in a very short period of time. This is particularly true if compared with the conventional mode of drawing the contact pieces themselves apart. In the present device the entire arc is always extended by twice the distance travelled by the insulating plate 11 after initial contact separation. Conventional devices moving the contact pieces apart extend the are only by a distance equal to only once the travel path of the separated contact pieces.

During the travelling of insulating plate 11, piston 16 is being introduced into the cylindrical space or cavity 14. As one can see from FIG. 2, this cylindrical space 14 snugly receives piston 16 so that any oil in space 14 is forced to move upwardly and in between and around contact pieces 3 and 4. Accordingly, the circuit breaking region is being additionally insulated after commencement of circuit breaking.

It can be seen that the combined eifect of strong cooling with simultaneous extension of the arc permits a drastic increase in arc voltage without excessive are extension. In other words, a high are voltage is not being produced in a manner requiring excessively large circuit breaker construction elements and housings.

It will be understood that the mode of propelling element-s 111, 16, .17 and 18 upwardly cause these elements to attain a rather high speed. Consequently, it is desirable to brake this movement so that no direct impact is to be taken up by any of the moving or stationary elements.

For purposes of braking, there is provided a spring 22 sandwiched in between two normally stationary .plates '23 and 24, which plates have central bores to slidingly receive rod 17 While plate 23 may be secured to housing 13, plate 24 is loosely seated on a collar 24a of tube 13. Rod 17 cannot carry plate 24 along by way of friction, since spring 22 urges plate 24 down and against the stationary collar 24a. However, during the last portion of the upward movement, piston .18 engages plate 24 from below and urges this plate upwardly thereby compressing spring 22. Accordingly, piston and rod will be braked.

Since insulating plate 11 is not secured to rod 17 nor to pistons 16 and 18, a separated braking device is provided for insulating plate 111. This braking device is of the liquid type and comprises the following elements and provisions.

Cavity 7 narrows down in upward direction to a rather narrow gap 25. The wall .11 moves into this gap 25 thereby compressing the oil therein. There is still nar' rower opening 26 through which the oil can escape. By suitably select-ing the size of opening 26 in [relation to the width of gap 25 the cushioning effect can be adapted to the speed of insulating plate 11 when entering gap 25.

Opening 26 has an additional function; when the circuit breaker housing is being filled initially with oil, air in cavity 7 can thereby escape upwardly. Thus, opening 26 ensures that gap 25 is really filled with oil and that no air is being trapped therein.

However, .it might be advisable to make provisions for an air bubble to remain in gap 25 for adjusting the braking eifect produced thereof. Such air bubble can be made to remain in having opening 26 not leading into gap 25 at the top 27 thereof, but slightly below thereof and from the side (see 'FIG. 1a).

As can be seen best from FIG. 3, the gap 25 is preferably wider than the insulating plate 11 is thick, so that some oil can escape lateral and flow downwardly when plate 11 enters ,gap 25. Thus, the relation between gap width and plate thickness further determines the degree of braking.

In the upper part of circuit breaker housing 9, there is provided a valve 9a protecting the housing from excess pressure, particularly gas and vapor developed during circuit breaking can escape through valve 9a.

FIGURE 6 illustrates a modification for the cavity 7 and its defining walls 5. The Walls 5 enclose oil filled cavity .7 rather narrowly so that the arc 2.1 is very confined therein. Apertures 8 serve as gas escapement as aforedescribed. The figure also shows the relative location of lead-in rods 1 and of contact pieces 3 and 4; circuit breaker housing and propelling device are not shown, but they are similar to those shown in FIGURES 1, 2 and 3.

In order to further narrow the cavity 7, there are short sleeves 30 consisting of or containing material which dispenses gas upon heating. As can be seen, any sleeve 30 is located to come very close to the arc 21 after are carrying edge 20 of plate 11 has passed by. There are shown three sleeves 30 spaced apart to define wider cavity portions in between into which subcavities terminate the degassing apertures 8.

Use of such gas dispensing substances reduces the amount of oil used since the liberated gas contributes materially to the extinguishing of the arc. Gas dispensing substances themselves are only little attacked by the arc nor is metal being deposited upon them.

In this embodiment there is also provided a narrow upper gap 25 being in the uppermost sleeve 30 and also serving a liquid brake. Above gap 25 there are positioned plates 31 consisting of elastic material, for example, of oil proof rubber. A spring 32 bears against the upper plate. Elastic plates 31 as well as spring 32 break the upward movement of insulating wall or plate v11, whenever plate 11 hits the lowest plate 31.

Each aperture 8 may be provided with pressure sensitive valves (not shown). Such valves will prevent premature gas and oil escapement from cavity 7, and a predetermined pressure will have to be exceeded in cavity before oil and gas escapes into the space of housing 9.

FIG. 7 illustrates a modification of the upper portion of wall 5, defining oil filled cavity 7. There are provided three separating walls 33, extending transversely to plate 1-1 and its direction of movement and-dividing the upper cavity into four chambers 34.

During circuit breaking, plate 11 traverses chambers 34 successively from below. The are is being extended thereby and deformed as indicated by the dashed line. There remain, of course, gaps 33a between the plate 11 and walls 33.

Gas developed by the arm in a chamber 34 will escape downwardly through these gaps 33a. In other words, the gas will escape in a direction opposite to that of movement of plate 11. When gas fiows from one chamber 34 through such gap into the chamber below, eddies are being formed in this latter chamber causing turbulent mixing of gas and oil in such chamber. The gas is vaporized oil produced by heating from the arc. Accordingly, the hot gas is being cooled by the relatively cooler oil upon mixing therewith. Hence, not only gas will flow down through gaps 33a but an oil-gas mixture will flow ult-imately into the lowest chamber 34.

Upon flowing downward, the cooled oil-gas mixture engages the arc in such gap 33a and a portion of the oil is being vaporized additionally. Accordingly, the arc is being cooled additionally. The gaps 33a have such crosssection so that suflicient gas and oil can pass indeed without undue pressure increase in any of the chambers 34. Of course, the stronger are walls 5, 6 and 33, the higher can be the pressure developed during circuit breaking, and, consequently, gaps 33a can then be narrower.

The uppermost chamber 34 has a roof traversed by cushioning-reducing channels 26 serving as upward gas escape as was explained above. No air bubble can remain in the upper one of chambers 34 when the cavity 7 is being filled with oil, and no gas cushion of excess pressure can be formed upon circuit breaking.

Proceeding now to FIGS. 8, 9 and 10 there are shown enlargements of the profile of leading or control edge or face 20 of insulating plate 11.

In FIG. 8, leading or arc-control face 20 has a channel 40 with triangular cross-section. The are 21 will be located in this channel 40. Thus, by provision of this channel 40 the arc is being maintained in the center of the upper edge of plate 11.

FIG. 9 illustrates a refinement in that the upper edge of plate 11 carries an insert 41 defining a channel 40 and consisting of or containing gas producing material. During upward movement of the plate 11, the arc is very close to this insert which upon producing and dispensing gas contributes to the cooling of the arc. In this case the main part of plate 11 will be made of material selected primarily to exhibit high mechanical resistivity.

FIG. 10 shows the upper part of another example for insulating plate 11, again there is carved a channel 40 into control edge 20 but there is metal traverse 42 introduced into the bottom of channel 40 so that plate 11 is endowed with further means for improving its mechanical resistivity. This is of advantage when, as was explained above, plate 11 does not only guide the arc, but also separates the contact pieces 3 and 4.

Experiments have shown that such metal traverse 42 in effect limits the arc voltage and equalizes the voltage drops per unit arc length along the extension of the arc.

Over-voltage and surge or lightning arrestor can be connected parallel to the circuit breaker.

FIG. 11 illustrates a different embodiment, again showing only cavity 7 defining means (walls 5) and contact pieces 3 and 4 in relative spatial orientation.

There are shown two insulating plates 11 respectively received by two communicating cavities 7 as defined by walls 5 and 6, so that the arc is being spread apart in a twofold manner. The two plates 11 are preferably joined at their bottom and propelled for circuit breaking by a common drive.

The embodiments of the invention as illustrated and described thus far, have not been shown in combination with any means for reclosing the circuit breaker. Those means have been omitted in order not to confuse the description of the circuit breaker proper.

These reclosing means will include means for returning the plate 11 into its resting position (FIG. 1). One simple measure may include a very strong rod introduced into any of the openings 26 pushing plate 11 down from above.

The propelling charge 19 can be replaced and renewed by a device analogous to that used in repeating guns.

Circuit networks employing high voltages to be applied to the electric conductors 1 preferably will include an additional switching device (see FIG. 1) connected in series with any of the rods 1, so that after circuit breaking the ,high voltage is not being applied continuously to contact pieces 3 and 4 and across plate 11. The said additional switching device 100 will be controlled so that upon complete current interruption by the circuit breaker, the additional switch 100 opens automatically.

Thus, the circuit breaker can be reclosed after the additional switch 100 has responded so that for completing the circuit later on, only the additional switch 100 has to be reclosed.

The circuit breaker according to the invention may be equipped with main and follower contact pieces as is known per se, so that the follower contact pieces have small mass.

As was said above, particular care has been taken to maintain a large arc voltage until the current is zero. The means employed in the above embodiments included an elongated oil filled cavity 7 as receiving space for the arc and a correspondingly long plate 11 capable of traversing the entire length of this cavity. This measure satisfies most requirements. In specific cases, however, one wants to have the arc voltage to follow through particular program. Particularly, one often wants an arc voltage which first increases rapidly to a particular value and then to remain constant at that level lasting during the major part of the circuit breaking action.

In the following it will be explained that the embodiments described thus far include measures with which the arc is subjected to static control effects so as to effectively control the arc voltage.

As was explained above, the arc voltage is primarily determined by the extent of cooling of the arc and by the rate with which the arc increases, i.e. by its extension in length per time unit.

Accordingly, the arc voltage can be controlled by controlling cooling or the speed of arc extension (speed of plate 11) or both.

The cooling exerted upon the are can, for example, be controlled by designing cavity 7 so that its offers a varying cross-section to the entering plate 11. For example, cavity 7 can be narrowed in the direction of advancement of plate 11.

It is pointed out that varying can be understood in two different ways. One is, that the cavity walls are stationary but positioned to narrow (or widen if desired) the cross-section along the path of traverse of the plate 11. The other way is, of having the walls 5, 6 defining cavity 7 made of resilient material so as to yield under any developing gas pressure in the cavity 7. Any of the embodiments illustrated are susceptible to this interpretation.

In case of a narrowing of the cavity the arc will be cooled more intensively as soon as the plate 11 with are 21 enters the narrower region of cavity 7. FIG. 1 and 6 actually show such narrowing of the cavity 7 below the respective gaps 25.

During circuit breaking, plate 11 will actually be slowed down by friction after the initial acceleration thereof. This slowing down results accordingly in a decreasing rate of arc extension. Also, the rate of cooling will be decreased when the speed of arc and plate movement is reduced. However, it can be seen, that an increased cooling because of narrowing of cavity 7 and a decreased cooling because of a slowing down of the plate are opposing effects which can be made to balance resulting in a constant arc voltage for a relatively long period of time. In other words, the reduced cooling due to the naturally slowing down of the plate 11 during circuit breaking, can be offset partially, completely or overcompensated as desired by suitably narrowing cavity 7 in direction of prospective plate movement.

In the embodiments of the invention to be described in the following there have been provided means for dynamically controlling the arc voltage and means are being employed to alter the flow of oil in dependence upon the progressing duration of the arc. Furthermore, the fiow of oil may be controlled indirectly but in dependence upon the electric current to be interrupted with a respectively stronger oil flow resulting from a higher current interrupted by the circuit breaker.

In FIG. 12, there is again shown circuit breaker housing 9 and an arc controlling plate 11 projecting into a cavity 7 defined by stationary walls 5. Walls 5 are here enclosed by a differential piston 47, normally resting on a ring-shaped abutment 9b of housing 9.

During circuit breaking, cavity 7 is subjected to the pressure of the gas constituted by vaporized oil; the vaporization results from the heat dissipation of the arc. This gas has, of course, a high pressure which is transmitted first through the lower aperture 8 so as to be effective below piston 47. This is, of course, due to the fact that immediately upon separation of contact pieces 3 and 4 the are still is in the lower cavity region, and gas is being developed right there at that lower region.

The upper space 51 as enclosed by housing 9 does not communicate with cavity 7. The pressure difference as effective on piston 47 will move the piston up since soon the gas pressure below thereof will prevail. Dash-dot line 48 denotes an elevated position of piston 47.

Simultaneously, plate 11 moves up into the dash-dotted position 49. Since the piston moves up with the arc, the driving effect from below will remain sufficiently long before the arc overtakes the piston.

During piston operation a sleeve 47a integral with piston 47 moves into a cylinder 50 which is integral with wall 5. Accordingly, the space defined by sleeve 47a and cylinder 50 is reduced as to its volume and oil flows through the upper aperture 8 into cavity 7. This oil flow is more intense, the more rapidly piston 47 with sleeve 47a moves upwardly. This piston motion, in turn, will occur more rapidly if more gas is developed below piston 47, and such more intense gas development, in turn, occurs when the arc is hotter and the electric current is a more intense one.

Accordingly, a more intense electric current to be interrupted will ultimately cause a higher oil flow for correspondingly more intense cooling. The differential piston thus provided aids in the production of an are having a high and constant voltage drop for a fairly long period of time.

It can be seen that in this embodiment the differential piston 4-7 pumps fresh oil towards the are for cooling thereof, and the pumping intensity is dependent upon the electric current in the arc, so that intensity of cooling, in turn, is dependent upon the amplitude of the electric current to be interrupted. Plate 11 is stopped by an oil brake having plate 45 and a spring 40.

The differential piston arrangement has, of course, an inertia as does have the oil, which inertia is not negligibly small. Furthermore, the piston moves in the oil and thus has to overcome the fluid resistance thereof. Thus, differential piston 47 will not be effective without some delay. This delay, however, is not at all a disadvantage.

At the beginning of a circuit breaking action, plate 11 is being accelerated to top speed in a very short time due to the use of detonating charges as propellant. Accordingly, the arc voltage increases rapidly up to a very high value. The differential piston is to become effective only when the speed of plate 11 starts to decline. On the other hand, an are developed immediately upon contact separation and heat is thus being dissipated long before plate 11 reaches top speed. A pressure increase develops below piston 47 immediately upon appearance of any arc; thus, by proper dimensioning, the piston can be made to actually set into motion as soon as the plate starts to slow down.

In case of small electric current, the differential piston need not be effective at all or be lifted only slightly from its seat. In case of a very small current it might even be undesirable to have piston 47 effective at all because the arc voltage is not to exceed values limited by the insulation provisions of the device. In other words, it is not always desirable to cool very extensively if the arc is only a rather weak one. Conversely, in case of large currents, no sudden reduction to zero thereof is to be expected because there are always inductances in the network to be discharged. Here now accelerated cooling is desirable and, in fact, is being produced.

Thus, in case of high currents more gas is being produced, faster and at a higher pressure than in case of small currents. Full forced flow of coolant is being produced by the diflerential piston when needed, while the differential piston remains more or less idle automatically when not needed.

One can readily see that the differential piston effectively places additional coolant into heat exchange relationship the more intensively the piston is being actuated upon by the gas developed by a high current.

FIG. 13 illustrates how one can make use of the known principle of electromagnetically blowing to further cool the arc. There is shown the tube defining the cavity 7,

and there is further shown a cross-section through plate 11 moving perpendicularly to the plane of the drawing. Cavity 7 has laterally extending gap-shaped enlargements extending in between the space of the poles of two electromagnets 52. The are 21 traverses these lateral extensions of cavity 7.

Magnets 52 when energized blow on the are and thus cool it additionally. Actually, the arc is being driven away from both sides of plate 11 and this does not only cool the are but extends it additionally.

The magnets 52 may be excited and energized by electric current flowing through coils 53 which electric current is being derived from the electric current to be interrupted itself, for example, by a bleeder circuit connected to the main circuit network upon commencement of circuit breaker action. In case the circuit breaker governs D.C., one could also use permanent magnets for the magnetic blowing.

Proceeding now to the description of FIGS. 14 and 15, there is shown a circuit breaker in which a strong liquid flow is being maintained for cooling so that a high are voltage is being maintained until the current is in fact being interrupted.

FIG. 14 illustrates the moment after insulating plate 11 has spread contact pieces 3 and 4 apart for circuit breaking and are initiation. The entire device is submerged in an arc extinguishing liquid such as oil. Plate 11 run in slots 12 (see FIG. 15) and in direction of the arrow in FIG. 14 during circuit breaking. The 21 is being extended during the upward movement of plate 11.

Plate 11 otherwise traverses a cavity enclosed by walls 54 having discharge channels 55 permitting fluid flow in a direction transversely to the extension and direction of movement of plate 11 as well as transversely to the axis of arc.

Channels 55 have different configuration. In the left hand portion they are defined by parallel straps 56 leaving horizontally extending flat gaps in between. The right hand. and rear portion of wall 54 are traversed by rectangular channels not quite square-shaped; they may also be round. This is shown for illustrative purposes only and neither uniformity nor non-uniformity of the channels is mandatory.

The front wall of the switch has liquid or fluid charge or inlet channels 57. In FIG. 15, the arrows 58 denote the direction of oil flow. The strong flow of oil cools the are considerably so that the arc voltage is drastically increased. The oil flow may, in fact, carry the are along to attain a position close to openings 55.

FIGS. 16 and 17 illustrate in more detail how a discharge channel 55 can be designed. Such channel may have wedge or groove-shaped. straps 56 leaving flat channel gaps in between. The grooves or wedges of the various straps 56 are aligned to receive arc 21 upon strong blowing. By means of inlet pieces the channels 55 may be limited laterally so that the entire fluid outflow passes very close to the arc (see arrows in FIG. 17).

FIG. 18 shows a layout similar to that of FIG. 15 but there is provided an additional wall 61 defining a space 62 containing additional detonating charges 63.

When fired, charges 63 produce a high pressure urging the extinguishing liquid through charge channels 57 into the arc cavity 7 and out again through discharge channels 55. This measure provides for a very intensive cooling of the arc.

The charges 63 are preferably rod shaped extending transversely to the plane of the drawing so that a more or less frontal shock wave propels the arc cooling and extinguishing liquid over an extended area against the arc along its entire extension, so that, in fact, a homogeneous cooling of the arc is produced, i.e., the arc is everywhere subjected to a similar liquid impulse.

FIG. 19 illustrates a still further modification in that there is only one such charge 63 inside a housing 61 extending around the left hand charge channels only. The space adjacent and outside of discharge channels 55 is enclosed by a deflector wall 64 laterally deflecting the outflow of fluid (see arrows). Now the right hand position of the arc and cavity is cooled by the thus deflected fluid. flow. Here, of course, the right hand portion of the arc will be cooled more than the left hand portion. Since the right hand portion of the arc is not only cooled by the gas developed upon detonation of charge 63, but also the gas developed by the left hand arc portion does, in effect, cool the right hand portion upon deflection by wall 64.

The invention is not limited to the embodiments described above but all changes and. modifications thereof not constituting departures from the spirit and scope of the invention are intended to be covered by the following claims.

What is claimed is:

1. A high voltage electric circuit breaker comprising; an outer casing which is at least partially filled with an arc-quenching oil, wall means of insulating material within said casing defining an elongated are burning and quenching chamber which is open at one end, current lead-in means extending into said chamber from opposite sides thereof and :lmaving normally interen-gaged contact pieces thereon adjacent the open end of said chamber, said contact pieces being adapted to be separated and when separated forming a gap therebetween in said chamber tand dnawing an arc therebetween across the said open end of said chamber, a plate-like member of insulating material between said wall means substantially in the plane of said gap normally spaced from said contact pieces and movable toward said contact pieces and through said gap and into said chamber so as to lengthen an arc in the gap between said cont-act pieces, and actuating means for moving said plate-like member toward said contact piec'es and through said gap and into said chamber beyond said contact pieces, said wall means having lateral bores therein on opposite sides of the plane of said plate-like member connecting said chamber with the space in said outer casing outside of said wall means for the circulation of oil between said chamber and casing, the end of said elongated chamber opposite to the contact pieces being substantially closed, and fluid displacement means operable for circulating quenching oil through said chamber :and lateral bores simultaneously with the lengthening of said arc by movement of said platelike member by said actuating means.

2. A circuit breaker as set forth in claim 1, wherein said wall means extend from the said open end of said chamber beyond said contact pieces and define an extension of said chamber on the opposite side of said contact pieces from said chamber, said extension of said chamber housing said plate-like member when it is retracted from said contact pieces and said contact pieces are closed, said fluid displacement means comprising a piston drivingly connected to said plate-like member at the end thereof opposite the contact pieces and cylinder means in said extension of said chamber for receiving said piston when said plate-like member is actuated whereby said piston displaces oil fro-m said cylinder means towards said contact pieces and into said chamber and through said l ateral bores into said casing concurrently with the movement of said plate-like member through said gap .and into said chamber.

3. A circuit breaker as set forth in claim 2, in which said fluid displacement means comprises a hollow cylinder in said casing, the interior of said cylinder being in communication with the ends of said lateral bores at the ends thereof opposite said chamber ends thereof, a movable differential piston element closing one end of said hollow cylinder, the side of said differential piston element facing away from the inside of said hollow cylinder being in communication with the environ of said contact pieces so as to be sensitive to the pressure developed in the region of said arc, said differential piston element being moveable into said hollow cylinder by the said pressure so as to force oil from said hollow cylinder through said lateral bores into said chamber and in a direction traverse to said are.

4. A circuit breaker as set forth in claim 1, wherein fluid displacement means is located in said casing on one side of one of said wall means :and is operable for causing oil flow into said chamber through some of said bores and out of said chamber through others of said bores.

5. A circuit breaker as set forth in claim 4 wherein said wall means have grooves on the sides thereof facing each other extending in the direction of movement of said plate-like member, said grooves being in registration for receiving the extended are.

6. A circuit breaker as set forth in claim 5 in which a first auxiliary chamber in said casing is provided communicating with some of said bores on one side of the plane of said plate-like member, a second auxiliary chamber con necting the other bores on said one side of the plane of said plate like member with some of said bores on the other side of the plane of said plate-like member, and an explosive charge in said first auxiliary chamber detonatable to expel oil from said first auxiliary chamber.

7. A circuit breaker comprising; a circuit breaker housing having quenching oil therein and having current leadin means and engageable and separable contact pieces thereon, insulation means defining an oil filled cavity in said housing and enclosing said contact pieces, a solid insulating wall in said cavity substantially in the plane in which said contact pieces engage each other, and said in sulating wall normally being spaced from said contact pieces and being moveable in said plane so as to traverse the region between said contact pieces when said contact pieces separate so as to carry the are developed between said contact pieces away from said region, wall means in said cavity on opposite sides of said insulating wall, discharge openings in said wall means communicating the space between said wall means with said cavity, and a groove in each Wall means on the side thereof toward said insulating wall, said grooves registering for receiving said arc.

8. A circuit breaker comprising; a circuit breaker housing having quenching oil therein and having current leadin means and engageable and separable contact pieces thereon, insulation means defining a cavity in said housing and enclosing said contact pieces, a solid insulating plate in said cavity substantially in the plane in which said contact pieces engage each other, and moveable in said plane so as to traverse the gap between said contact pieces when the contact pieces are separated thereby carrying the arc developed between said contact pieces away from the space directly between said contact pieces to lengthen said are in said cavity, said cavity having apertures therein communicating said cavity with the housing and defining a flow path across said are and transversely to the movement of said plate, actuating means connected to said plate for moving said plate to cause it to lengthen said are and fluid displacement means also actuated by said actuating means, means operable for propelling said quenching oil through said apertures simultaneously with lengthening of said are by movement of said plate.

9. In a circuit breaker; a housing containing quenching oil, insulating wall means in said housing spaced from the walls of said housing and defining a cavity therewithin, said cavity being open at one end, electrical lead-in means leading through said wall means on opposites sides of said cavity at said one end of the cavity and having normally engaged contact means at said one end of said cavity, a plate of insulating material between said wall means on the opposite side of said contact elements from said cavity and disposed in a plane passing substantially through the region of engagement of said contact elements and along the axis of said cavity, actuating means connected to said plate operable for moving said plate in said plane toward said contact elements and between said contact elements and on into said cavity, thereby to elongate an are drawn between said contact elements upon separation thereof, lateral bores in said cavity communicating the cavity with the interior of said housing, and means operated simultaneously with said actuating means and operable for causing flow of quenching oil through said lateral bores at least in the region of that portion of said plate which is extending the are between said contact elements, whereby the movement of the plate lengthens the said are and the movement of the quenching oil quenches the said arc.

10. A circuit breaker according to claim 9 in which said wall means support and guide said plate and said wall means have grooves in the sides thereof facing each other and in registration and in said cavity and adapted for containing and directing said are as it is drawn into the said activity by the movement of said plate.

References Cited by the Examiner UNITED STATES PATENTS 1,696,604 12/ 1928 Hilliard 200- 1,833,173 11/1931 Murray 200-153 2,104,914 1/ 1938 Temple 200-150 2,106,531 1/1938 Leeson et al. 200-150 2,134,179 10/1938 Evans et al. 200-166 2,277,422 3/ 1942 Walle 200-151 2,284,347 5/1942 Strom 200-151 X 2,477,837 8/1949 Strom 200-151 X FOREIGN PATENTS 1,118,316 11/1961 Germany.

385,478 12/ 1932 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

ROBERT S. MACON, Examiner. 

1. A HIGH VOLTAGE ELECTRIC CIRCUIT BREAKER COMPRISING; AN OUTER CASING WHICH IS AT LEAST PARTIALLY FILLED WITH AN ARC-QUENCHING OIL, WALL MEANS OF INSULATING MATERIAL WITHIN SAID CASING DEFINING AN ELONGATED ARC BURNING AND QUENCHING CHAMBER WHICH IS OPEN AT ONE END, CURRENT LEAD-IN MEANS EXTENDING INTO SAID CHAMBER FROM OPPOSITE SIDES THEREOF AND HAVING NORMALLY INTERENGAGED CONTACT PIECES THEREON ADJACENT THE OPEN END OF SAID CHAMBER, SAID CONTACT PIECES BEING ADAPTED TO BE SEPARATED AND WHEN SEPARATED FORMING A GAP THEREBETWEEN IN SAID CHAMBER AND DRAWING AN ARC THEREBETWEEN ACROSS THE SAID OPEN END OF SAID CHAMBER, A PLATE-LIKE MEMBER OF INSULATING MATERIAL BETWEEN SAID WALL MEANS SUBSTANTIALLY IN THE PLANE OF SAID GAP NORMALLY SPACED FROM SAID CONTACT PIECES AND MOVABLE TOWARD SAID CONTACT PIECES AND THROUGH SAID GAP AND INTO SAID CHAMBER SO AS TO LENGTHEN AN ARC IN THE GAP BETWEEN SAID CONTACT PIECES, AND ACTUATING MEANS FOR MOVING SAID PLATE-LIKE MEMBER TOWARD SAID CONTACT PIECES AND THROUGH SAID GAP AND INTO SAID 